Studies show patients with low-risk heart problems can be sent home within four days.

But medical staff Fazakerley hospital and Royal Liverpool hospital say some patients need to stay longer.

Research in the Lancet medical journal said studies outlined how early discharge of low-risk heart attack patients was feasible after four days with no additional risk.

But the research from Alberta university in Canada found wide variations between countries.

The most recent trial showed the number of potentially unnecessary hospital days per 100 patients ranged from 65 in New Zealand to 839 in Germany.

Dr Adam Times, of London's Chest Hospital, said that because of a lack of facilities and trained staff in the NHS, many UK patients were staying in hospital even longer than revealed in the Lancet study.

He said: "There are also important inefficiencies built into the UK system of coronary care, with unavailability of senior staff at weekends to make or implement discharge decisions, thus often prolonging by up to three days the hospital stay of patients."

But today hospital staff in Liverpool argued that a cut-off point of four days for patients would be "ridiculous".

A spokesman for Royal Liverpool hospital said: "Patients are treated as individuals.

"A lot of our heart attack patients are frail and elderly people who have got other complications.

"As a consequence, it might be necessary to keep them in because of their ability to cope.

"We wouldn't want to prescribe a cut-off point for patients, that would be ridiculous."

A spokeswoman for Fazakerley hospital added: "People who have had a heart attack with no complications would be likely to be discharged within five days.

"If they needed investigations they would be kept in longer. Patients are kept in as long as they need to be."